BQ76PL536EVM-3: BMS with MSP-EXP430F5529LP Comms

Raheem Hall

Part Number: BQ76PL536EVM-3
Other Parts Discussed in Thread: BQ76PL536, BQ76PL455A,

Hello Forum

I am attempting to make a battery management system using the BQ76PL536EVM-3 and MSP-EXP430F5529LP, using the application report SLAA478.

So far, I've removed resistors R49, R53 and R60 from the 'PL536, and I have modified the software available to use P1.5 instead of P1.1 (on the MSP430 LP) for the FAULT signal from the 'PL536.

However, when everything is connected, I am not seeing any data being sent to the host PC via USB (verified using PuTTY). In fact, using CCS, I am not seeing the any of the 3 bq76PL536 devices being assigned an address in the code.

What does happen, however, is that the red LED on the MSP430 LP (P1.1) switches on and stays on (implying a connection/communication problem between the MSP and BQ). Also, some cells connectd to the 'PL536 EVM seem to be discharging through their balancing resistors, even though their voltages are lower than the other cells in the pack.

Has anyone experienced this? Does anyone have a solution?

over 8 years ago

0 Roger Hwang over 8 years ago

TI__Genius 10785 points

Have you post your question to microcontroller/map430 forums.
I think you have HPA507A evm.
If yes then measure the voltage between TP-VPROG1 and TP-VSS1.
I want to make sure IC is Okay.

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Hello Roger

Thank you for replying. I took the measurements as requested.

Between TP-PROG1 and TP-VSS1, I'm getting 4.965V.

Between TP-PROG2 and TP-VSS2, I'm getting 2.2 mV.

Between TP-PROG3 and TP-VSS3, I'm getting 5.126V

Regards

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Hello Roger

Thank your for replying. I took the measurements as requested.

Between the TP-VPROG and the TP-VSS1 pins I'm getting:

IC 1 (cells 1-5): 4.965V
IC 2 (cells 6-10): 2.2mV
IC 3 (cells 11-15): 5.126V

Regards

0 Roger Hwang over 8 years ago in reply to Raheem Hall

TI__Genius 10785 points

It seems like your IC2 is dead. Which means you have to replace the IC2 for you to communicate to IC3.
Your IC1 looks okay so you should be at least able to communicate to bottom IC.

Do you have Aarvark?

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Hello Roger

No, I do not have an Aardvark adapter. The only way I can 'communicate' with the EVM is through the MSP-EXP430F5529 LaunchPad.

I guess the next step then, is to replace IC2. The only material I would require is another bq76PL536 IC, correct?

If I may ask, what exactly may cause a single IC to go bad? I am certain I had made the recommended connection to the EVM, using the screw adapters available. If it was an incorrect connection, wouldn't IC3 go bad as well? Though it is unlikely, can a coding issue cause this?

Regards

0 Roger Hwang over 8 years ago in reply to Raheem Hall

TI__Genius 10785 points

Yes, you have get a sample and replace.
Your coding will not damage the IC.

Remember, it has separate power GND for each device so incorrect connection may damage the IC.
Again, you can still debug the code with Launchpad.

all you need is SPI connection to PL536A.
Check the CS_H, CLK and SDI.

Does MSP code looking for 3 devices?
Check and make sure you are only addressing for 1 IC

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Understood.

Would this (www.digikey.com/.../2679320) be a suitable replacement for IC2?

Since I did not know about this before today, the code was still looking for 3 devices. I will change this to 1.

Thank you for the assistance.

Regards

0 Roger Hwang over 8 years ago in reply to Raheem Hall

TI__Genius 10785 points

Yes, that will work.

What is your application?

How do you power up the device?

Are you using cells or PS?

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Hello Roger

My intended application is a battery management system designed to monitor 15 series Lithium Iron Phosphate cells (15S LiFePO4). The setup is shown below:

As per the instructions in sluu437d, the tap-off points are inserted into mating connectors with screw terminals, then secured by tightening the screws. The mating connectors are then inserted into the corresponding jacks on the bq76PL536EVM.

Regards

0 Roger Hwang over 8 years ago in reply to Raheem Hall

TI__Genius 10785 points

This will work but have you reviewed bq76PL455A.
This is 16S AFE that you only need 1 IC.
You might want to check out.

Yes, your system design is okay too.

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Hello Roger

Thanks for the recommendation. That board was considered, but I ultimately went with the bq76PL536EVM-3.

Thank you for your assistance in diagnosing the source of the problem I was having.

I do have one final question. Is there any way to test the isolated communications interface area on the lower left section of the board, to know if it is functional?

Regards

0 Roger Hwang over 8 years ago in reply to Raheem Hall

TI__Genius 10785 points

You checked the LDOD which is good. It means IC is not dead.

You have to write/read now.

0 Raheem Hall over 8 years ago in reply to Roger Hwang

Intellectual 550 points

Okay then.

Thanks for the assistance in diagnosing the board. Turns out the communiation error itself was due to incorrect placement of the jumpers JP19 and JP20 on the isolated communications interface. Nevertheless, IC2 is still dead, and I am getting a replacement.

Regards

Power management

Power management forum

BQ76PL536EVM-3: BMS with MSP-EXP430F5529LP Comms